[engine_work] Xu9j4 Mi-16 Rebuild

[welshpug 1,657]

very simple answer, hotter plug fouls much less easy

[kyepan 291]

Three intact and one that appears to have either pinched on the way in

or has pinged apart. It was cam belt end number one cylinder.

 

Either way it doesn't explain the idle / part throttle and start issues as one cylinder can't throw the whole lot out that much and if it did it would only misfire on one.

 

I'll make sure it goes back together with a suitable quantity of mastic on the mating surfaces, as there really wasn't much to speak of.

 

 

The offending artcile below, the others looked fine.

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The warmer plugs continue to start just fine, however under duress they do not perform as well as the cold ones, a lack of power is noted at the top end on a short spirited drive over some hills.

 

I'll plug the lap top in next week and check all the sensors are reading correctly.

[Paul_13 212 1 Cars]

Tps reading ok through the range

[ftoomsh 5 1 Cars]

I'd just put an extra shim under each spring. That usually puts them back in spec. after a long life and rebuild. I've tested many springs.

Would this not increase the risk of them becoming spring bound ie completely compressed with all coils touching? ?

[kyepan 291]

No, in a word, the shim is about 0.5 MM tall and the Spring has plenty of compression left when it's fully depressed.

[petert 586]

Correct. A standard Mi16 cam has 9.20mm of lift. The standard spring can handle approx 11.00mm of lift safely. Thus there is considerable safety margin for jacking up the spring by another 0.5mm.

[kyepan 291]

Sorted the cold start issues.

Sorted the o rings, proper sized ones and seated them as per satchell's instructions with a little silicone grease.

Also swapped the alternator over and it's cleared the boggy misfire up a treat.

 

So finally it's running pretty much as it should.

[allye 530 3 Cars]

I admire your relentless trouble shooting with this!

 

With stupid little issues I get wound up and have to walk away and come back to it!

[kyepan 291]

Yeah I park it and take the other car when it pisses me off, I've cracked a weld on the manifold too. And also replaced a very deteriorated injector omring that's helped a little

[Banjo 1]

Wow you've really been through a lot with this, a sucka for the hammer !

[kyepan 291]

yeah a bit, but it's worth it for the hammer, when it runs right it's just amazing.

[kyepan 291]

Ok, so..... after about 6 hours of driving all the issues gradually re-emerged... WTF... but It's now sorted.

Short version is - exhausts that aren't quite right on pulse tuned cars can give you massive flat spots and once you've eliminated all the electrical possibilities use your bloody eyes and ears and find the physical ones.

In short the car was off the boil, not running right, sounding farty, and generally running sluggishly, lots of throttle for little go... Plus it gradually developed a big flat mushy flat spot when you snapped open the throttle at low RPM....FML

I've also spent a load of time getting the correct o rings, and seating it properly, getting them just right, and that helped a lot, however the bodies sounded like they still had a leak. Also I remembered i nipped up the spindle bolts to make sure that they were okay, and there was some slack in them, more on that later.

So after the Orings were sorted and the issues re- emerged. After much electronic trouble shooting i ruled out the following.

Wrong heat range plugs

Coil pack failing

Coil pack earthing

Leads

TPS - put a trace on it on the DTA software and watched it, it was solid.

Water temp sensor..

air temp sensor....

As i got down to the last of those i felt it might be something physical, because when i'd nipped up the bodies it was really better, so i went back and started looking more closely at them. Now their 98 spec bodies, quite a few years old, and have probably been on my car for 4 years, and another car for god knows how long before that. Ie... perhaps they're not as golden as they would seem...

It turns out they were not very golden at all, more brown. I could hear the damn things leaking, if the o-rings were sorted, then it must be from the spindles. And sure enough, there was play. A brief search shows that sometimes they can be rebushed with teflon, or bearings pressed in, but really realistically that wasn't economically viable.

here's a video of the play... looks fairly minor, i can assure you it affected it drastically.

A video, with some camp person speaking on it.

http://vidmg.photobucket.com/albums/v152/kyepan/A15AA3C0-FB74-446E-82BB-55A78B588669_zpsnsrlwm68.mp4

Now if i've been checking them regularly and finding them gradually going out of balance, and rebalancing them, when they wern't going out of balance. They were getting more and more worn and leaky.. I end up with some very wrongly set bodies consequently being out of phase with the map, and issues galore.

Fine - so onto ebay

- new set of bodies for just over a hundred quid, and swap them over, done. The new bodies had no play, thankfully and so i was confident they would fix the issue.

‹

As they came to me

​

All cleaned up

Now the actual swapping took a bit more effort than i anticipated, considering getting the throttle quadrant off was a challenge as it had been tack welded on and the nut was not very proud.

undoing that nut looks simple enough..

​

Ahh hang on a minute perhaps not.

​

Getting the trumpets out posed a larger issue, i'd used mastic to hold them in, way way too much, and they really weren't going anywhere, the trumpets came apart, but the throats were really not moving.

Mole grips with rag padding - no joy.

​

Heat on the casting and water on the trumpet - No joy.

Angle grinding the bodies apart very very carefully so as not to damaged the trumpets - all sorts of joy.

And mess

​

But then they were only fit for the bin because of the spindle wear, so i guess no waste really.

Here are the separated trumpets together with the new assembled bodies with quadrant.

Putting them back together involves seating them square, elsewise the o rings pinch top or bottom, it's taken me a few goes to get the hang of it but two mole grips and gradually increasing force gets them in nicely and then they're held together with a few screws.

​

As with all major works on the car i set myself a girlfirend related deadline, it was to pick her up from the station at 8:39pm.. it was 8pm and the car had not started, back together, but the throttle pot needed calibration and the bodies needed balancing.

Now i've been Dicking about with these (probably to sandy's consternation) for the past few years, and i never once considered to find out exactly how suzuki said you should do it, so onto the internet i went, and armed with the correct information i set about doing them individually on the bleeds, then balancing the left pair, the right pair, then both pairs via the left, right and then centre adjuster.

Bleed screws.. i checked the existing bodies before i started, and these appear to be set around a full turn and a half, so 540 deg. That would be my starting point and i would balance from there.

Listening down the trumpets with a length of hose to the bleed screws, you can hear when they are passing the same amount of air because the pitch of the whistle and the volume of the whistle is the same, a couple of very minor tweaks to the turn and a half and we're in business.

Then balancing, now again using your ears you can hear the tack tack of the cylinder coming back up the throat and the angle of the butterfly determines how much volume and definition of the tack. Once you have these both right and set to five on the snail gauge which is what sandy set it to, you're in business.

Cylinder four has a bit more TACK than the others, could be a slightly blocked bleed, I checked the bleed later and it appeared clear, so surmised that may be to slack in the linkages, . as their connected in series, but other than that, it was pretty spot on flow wise.

It would blip freely on very little throttle and the hydrocarbon smell disappeared, we're cooking with petrol.

Onto a test drive, ok, still a massive flat spot, but, it sounded right at the top end, really really crisp bark, hammer jesus it was fast.. it was back.

Bearing in mind i'd had the Manifold fixed, and also this hi lighted the annoying exhaust rattle, Paul 13 mentioned he'd had a flat spot from an exhaust before, so i booked in to have the offending box replaced... Sure enough the chap at long life tapped it and said it was borked. He also mentioned the flange was bent and leaking which i'd noticed but discounted, no doubt from it's meeting with the kerb, he said he would seal it up as best as he could but.. it would go.

Here is a video of the offending box.... as you look down it you can see its all still in once piece... but the wadding has been blown to bits and is rattling about

http://vidmg.photobucket.com/albums/v152/kyepan/7A2655F5-18B8-4B66-AF0E-909AA290336B_zps2grsrky4.mp4

So, after the exhaust was fixed, it was right, no flat spot, everything good, So....as it blew the sealent out the flatspot returned, not as bad but still there.

A week later it went back for a new flange and now it's mega.

Physical wear happens over time, and it's so hard to spot especially on a tuned up car.

It also highlights one of the advantages of the bike bodies - plentiful cheap replacements, and the drawbacks, slightly custom fitment and fixings. There's another set on ebay this week that is even cheaper.

I hope this helps others with bike bodies, or bodies in general track down running gremlins as it's really taken the enjoyment out of the car for some time.

Cheers

Justin

[GLPoomobile 958]

Think this is appropriate

 

"Dedication. Dedication. Dedication, that's what you need"

 

Or this

 

"Cor what I like and what I hate about perseverance
Ooh what I'd give and what I'd take for perseverance"

[petert 586]

Epic. Well done.

[kyepan 291]

Thanks chaps. What's the second quote from GLP? Fred Dibna?

[opticaltrigger 52]

Excellent article Kyepan,

Thanks very much for posting it.Great that you got it done.

 

All the best

O.T.

[kyepan 291]

OK - so a small flat spot has returned - so the sealant around the manifold to flexi flange must have failed, exhaust is sounding less quiet too... so i know it's there.

 

Initially they used silicone high temp sealant, when the flange was bent, then the same stuff later on when they changed the flange, i needed to take it off to get at the beam as it was being rebuilt a couple of weeks ago and used the paste that sets solid....

 

Now because the manifold is super long, it goes way under the car, all the force from the engine goes down through the flange and flexi... so i'm after a bit of advice.

 

Because of all this bending, i think yes winding it up solid is a good idea, using only minimal gasket sealant is also an idea, so as it flexes it doesn't then have space to leak into..

But - should i consider using one of those graphite cored gaskets? would that give a longer life of seal and cope with all the flex and pressure better than mating faces and sealant?

 

Otherwise it will be a case of cleaning it up, putting silicone on it, not much though... and then wanging it up FT.

 

Thoughts?

 

Secondly it lost it's crispness of bark... and sure enough the right hand pair of bodies went very slightly out of balance, dad suggested a bit of enamel paint on the backs of the adjustment screws to hold them in place... there a bitch to get to from behind TBH, Not really somewhere i could get thread lock in to,, unless it's on a brush.

 

I think i'm going to set them and photograph the positions of the screw heads, then next time it goes out of balance i'm going to see what's moved... again thoughts.

 

I feel i'm nearly there on how to get this lot set up and set up right, for the long term... When it goes off the boil i now know why

 

Cheers

J

Edited April 19, 2016 by kyepan

[welshpug 1,657]

can you refresh our memories as to what the exhaust looks like? using sealant doesn't sound right to me, a gasket would be better.

 

I would be tempted to add some flexi joints in the secondaries.

[kyepan 291]

Yep sure,

 

I don't have a photo of it in the present configuration but it's arrangment is as follows

 

[Manifold 4] - [ 4 into 2 collectors] - [2 into 1 collector] - [2 inch pipe] - [Flange] blow here [Flange] - [Flexi] - [Front box] - [Mid pipe] - [backbox]

 

This is an old photo, as you can see it didn't have a flexi, or flanges, or the full system.

​

 

That's dave who owns maniflow, he built the manifold.

Edited April 20, 2016 by kyepan

[welshpug 1,657]

I'd get one of these in as close as you can to the 2-1 section, and add a gasket to the flange, is it a normal flat 2 bolt thing?

 

 

 

(that's my BMW's downpipe, had a flexi originally but after 23 years and 104k it split inside, replacement was larger i.d than original at the same pipe join diameter, I have added the same to the base of my 205's magnex.)

[kyepan 291]

So I have a flexi like you shown, yep the flange is standard two bolt, I'll get a gasket... Any idea where to get a two inch one from and do they come in standard sizes for the bolt spacing?

[petert 586]

Why can't you cut and shut a regular doughnut flange in after the 2-1 collector?

[welshpug 1,657]

https://www.clampcouk.co.uk/exhaust-repair.html

 

 

 

loads of different 2 pin exhaust gaskets here, you need to measure the bolt spacing.

 

https://www.clampcouk.co.uk/two-pin-exhaust-gaskets.html

Edited April 20, 2016 by welshpug

[kyepan 291]

Why can't you cut and shut a regular doughnut flange in after the 2-1 collector?

i probably could, is there an advantage to that over a flat flange?

[kyepan 291]

https://www.clampcouk.co.uk/exhaust-repair.html

 

 

 

loads of different 2 pin exhaust gaskets here, you need to measure the bolt spacing.

 

https://www.clampcouk.co.uk/two-pin-exhaust-gaskets.html

Thanks Mei